PAINTING

k is it me or does every1 else have this problem? I use testors paint and b4 I paint my customs I wash n prime them but when I apply red, yellow, orange, white -(warm colors) the paint looks like crap. n sometimes when I apply multiple coats it takes away the 1 b4 it. is there a certain primer color I have to use for a certain color? let me know, thanx.